This invention relates to abrasive products.
Abrasive compacts are well known in the art and are used for a variety of abrading operations such as cutting, drilling, grinding and the like. Abrasive compacts consist of a poylcrystalline mass of bonded abrasive particles, the abrasive particle content generally being at least 70 percent by volume and more particularly 80 to 90 percent by volume. The abrasive particles may be self bonded without the aid or use of a second or bonding phase. Alternatively, a second or bonding phase may be provided. The abrasive particles for compacts are invariably diamond or cubic boron nitride.
Abrasive compacts may be bonded to cemented carbide supports. Such bonded compacts are often referred to as composite compacts. Bonding between the compact and the carbide support may be direct or a bonding layer of a suitable braze may be provided between the compact and the carbide support.
Abrasive compacts and composite compacts are described and illustrated in a number of published patent specifications, for example U.S. Pat. Nos. 3,743,489, 3,767,371, 4,063,909 and 3,745,623.
Diamond abrasive compacts which contain a second phase of a diamond catalyst/solvent tend to degrade at temperatures exceeding 700.degree. C. Diamond abrasive compacts which are thermally stable at these high temperatures are known and are described, for example, in U.S. Pat. Nos. 4,534,773, 4,224,380 and British Patent No. 2,158,086.
U.S. Pat. No. 4,673,414 describes a method of making a re-sintered CBN compact which comprises providing a batch of boron-rich polycrystalline CBN particles and sintering these particles at a pressure and temperature adequate to re-sinter the particles, the temperature being maintained below the reconversion temperature of CBN. The method is said to result in the formation of superior polycrystalline CBN compacts without the aid of a catalyst at pressure and temperature conditions which are typically employed in processes which utilise a catalyst. The method is restricted to the use of boron-rich polycrystalline cubic boron nitride particles.